This invention relates generally to wireless communications, and more particularly, ensuring that user equipment selects optimum cells with which to communicate in a cellular telephone network.
Cellular telephones and other wireless electronic devices handle voice and data communications using cellular telephone networks. Older 2G networks and newer 3G networks use different communications schemes. When both types of networks are available for supporting communications with a given user device, it is generally preferably to establish a 3G link with the device rather than a 2G link. This is because 3G networks tend to offer superior communications capabilities such as potentially higher data rates.
Cellular networks are deployed in geographic regions called cells. In a given network, each cell is used to cover a different region. For example, in a 2G network, there are numerous cells, each of which has a respective 2G base station. There is some coverage overlap to avoid dropped calls as a user transitions between cells, but each cell is essentially distinct.
So as to provide a seamless transition to newer network technologies, 3G networks are typically deployed on top of existing 2G networks. For example, heavily traveled urban corridors may be outfitted with 3G base stations to supplement 2G service. In less populated regions, 3G service may not be available. As networks build out their capacity, 3G base stations are constantly being added. Because the number and location of 3G cells in the network changes frequently, it can be difficult to keep track of the current state of the network, particularly when numerous organizations are involved in deploying and maintaining service.
Despite these difficulties, networks attempt to maintain lists of active cellular sites. For example, a network may constantly broadcast a list of nearby 3G cells that are available. User equipment that receives the broadcast list can attempt to establish a communications link with one of these 3G cells, thereby allowing the equipment to switch from 2G to 3G service. Due to the rapidly changing nature of the 3G network, however, the broadcast lists of available 3G cells may contain inaccurate information such as omitted 3G cell sites. This can make it difficult or impossible for user equipment to accurately identify available 3G cells without performing continuous frequency scans.
It would therefore be desirable to be able to provide improved techniques for identifying available cells in a network, particularly in environments that contain a mixture of different types of cells.